Safety joint for use in oil well tools



April 20, 1965 HART SAFETY JOINT FOR USE IN OIL WELL TOOLS 2 Sheets-Sheet 1 Filed Aug. 13, 1962 INVENTOR. PQINCE' A H1427" WZZW I SAFETY JOINT FOR USE IN OIL WELL TOOLS Filed Aug. 13, 1962 2 Sheets-Sheet 2 Fi .4 Tia-5 INVENTOR. Fem/ca d, HAer United States Patent 3,179,180 SAFETY JOINT FOR USE IN 0H. WELL TOOLS Prince J. Hart, Chickasha, Okla assignor to James, Inc, Oklahoma City, Skim, a corporation of Oklahoma Filed Aug. 13, 1962, Ser. No. 216,622 13 Claims, ((1166-2113) This invention relates to a safety, joint for use in oil well tubing or drill strings for the connection in such strings of such devices as packers, anchors and catchers. More particularly, but, not by way of limitation, the present invention relates to a safety joint which is adapted to be permanently connected in a string of oil well production tubing in combination with a mechanism which functions dually as an anchor and a catcher for the tubing string.

In oil well drilling and oil production operations, it is customary practice to make up a drill string or tubing string by connecting sections of tubing or drill string together through a plurality of threaded joints. These joints involve male and female threaded end parts on the tubing sections which parts, are screwed together to make up the complete tubing string.

It is also customary in the petroleum production and drilling technology to frequently include tools or imple ments of various types within the tubing string by coupling such instruments into the string using threaded joints. The operation of such tools oftendepends upon the rotation of the tubing in one direction or the other in order to actuate certain mechanisms within the tools. It is therefore necessary that consideration be given to the design of joints and actuating mechanisms in such tools so that the section of tubing or drill string will not be inadvertently unscrewed during the operation of the tool to permit the tubing string to be parted and the lower portion thereof to be dropped into the well. Situations in which a tubing string is parted or is carelessly lost into the well bore by rotating a tubing section in the wrong direction (counterclockwise when the sections of the string are connected by standard A.P.I. threads) are well known and, in each instance, may result in a loss amounting to thousands of dollars. Such losses entail an expensive fishing job to remove the lower section of the tubing string from the bottom of the well and, in most instances, the complete destruction or incapacitation of the tubing section which is dropped.

In order to reduce the possibility of operator error in operating subsurface oil well tools by incorrect rotation of the tubing string at the surface of the well, a number of joints of various types have been provided with the object of transmitting the rotary motionof the upper portion of the tubing string to the actuating mechanism of a particular type of oilWell tool without there resulting accidental parting of the tubing string. However, in most instances, the possibility of operator error has not been eliminated, and there still frequently result cases of tubing strings being parted and being lost in the Well bore.

One of the types of oil well tools with which the problern of parted tubinghas been most frequently associated have been those tools or devices known as anchors. The purpose of a tubing string anchor is to maintain the tub ing string in a fixed position relative to the surrounding walls of the well casing, and to absorb vibration and excessive stress applied to the tubing during operation of the oil well pump. In reducing movement of the tubing string relative to the well bore, the anchor also reduces the wear on the sucker rod of the oil well pump, reduces the frictional wear between the tubing and the oil Well casing and protects the tubing from being over-stressed as the hydraulicload imposed by the oil in the pump is transferred from the rod of the pump to the tubing.

Such tubing anchors generally utilize a plurality of mandrel means.

ice

slip elements which are toothed or wickered members which may be expanded radially relative to the tubing string to engage the walls of the surrounding well casing. The outward movement of the slips is effected through a mechanism which is actuated by the rotation of the tubing string at the surface of the well. After setting the anchor by rotation of the string in one direction, it is common practice to retract the slips to release the anchor by rotating the tubing in the opposite direction. It will be thus apparent that with such bidirectional rotation of the tubing, unscrewing of the jointsof the tubing string may be inadvertently brought about by a careless operator with the result that the lower portion of the tubing string falls down into the well bore and must be retrieved at a relatively high cost. Iumost instances, the anchor is allowed to remain set, the upper portion of the tubing is unscrewed, and then a special fishing tool is passed down the well bore and the anchor is released by the use of such tool and the lower portion of the tubing removed from the well bore. This operation, of course, constitutes a time-consuming and expensive endeavor.

Because of the possibility of the lower portion of the tubing string being separated or parted from the upper portion thereof, either through operator inadvertence, or because of metal fatigue and stressing of the tubing string, it has become a widespread practice to provide, in conjunction with the anchor mechanism, a catcher mechanism which functions to catch the lower portion of the tubing before it can fall any substantial distance downwardly in the Well casing. Such catcher mechanisms, like I the anchor mechanism, rely upon the actuation of radially movable slips which move radially outward from the peripheral surface of the tubing string and bite into or engagethe surrounding casing. t

The present invention provides a safety joint for use in tubing or rod strings which are rotated to actuate various mechanisms connected in the string, which safety joint prevents accidental parting or severance of the string by a careless operator. The invention further contemplates the combination of the novel safety joint with an improved anchor-catcher mechanism for use in an oil well tubin string.

Broadly, the present invention comprises actuating mandrel means which is connected at one of its ends through reversely threaded sleeve means to one section of the tubing in the tubing string and is connectedat its other end to another section of tubing. By reversely threaded sleeve means is meant a tubular member which is threaded at its ends with threads having opposite pitch so that the members to which it is threadedly connected (the mandrel means and said one section of tubing) will be backed away from each other when the tubular member is rotated and one or both members threadedly engaged therewith are held stationary. The mandrel means includes a locking means, which in one embodiment of the invention is a lock nut threadedly engaged with the end of the mandrel means which is threaded into the sleeve means, which locking means, during the operation of the safety joint, engages a protruding surface inside the sleeve means to prevent the mandrel means from becoming completely disengaged from the sleeve means.

In combination with the safety joint thus constituted, there is provided an elongated housing which surrounds the sleeve means and mandrel means. The housing carries a mechanism which may be selectively actuated by predetermined increments of rotation and axial movement of the tubing string. In a preferred. adaptation of the safety joint of the invention, the mechanism carried by the housing includes anchor slips which may be radiallyextended and retracted in response to movements of the tubing string transmitted through the sleeve means to the The novel construction of the elon- 3 gated housing and the mandrel means and their relative arrangement in the combination permits the slips to also function automatically as a tubing catcher device should the tubing for any reason be parted.

t is a major object of thepresent invention to provide a safety joint which may be utilized in an oil well tubing or drill string conjunctively with tools which depend upon rotation of the tubing string for their actuation, which safety joint assures against inadvertent separation of the tubing string by'erroneous rotation thereof by an operator.

A further object of the present invention is to provide a safety joint which is incorporated in an oil well tubing stringin combination with a novel anchor and catcher mechanism in such a way that the anchor mechanism may be set by rotation of the tubing string at the surface of the well without fear of under any circumstances parting the tubing string by improper rotation thereof.

A more specific object of the present invention is to provide an anchor for strings of oil well tubing and the like which shall completely overcome the possibility of separating two sections of the tubing string by eliminating the necessity for, reverse rotation of the string in order to release the anchor preparatory to withdrawing the string from a wellbore.

'An additional object of the present invention is to provide asafet'y joint for use in combination with an oil well tubing string anchor or the like which will be permanently attached to a tubing string without danger of accidental separation therefrom occurring upon reverse rotation of the string. 7

An additional object of the present invention is to provide an anchor safety joint for use ,in a string of oil Well tubing, which anchor may be successively set and then released in the well bore by successive increments of rotation of the tubing string in the same direction.

A further object of the present invention is to provide an oil well tubing anchor mechanism which does not require the use of shear pins for its release and neither requires the use of jarring or vibration to eifect its release. A further object of the present invention is to provide a safety joint to improve the safety and economy with which an oil well tubing anchor and catcher mechanism may be utilized, which safety joint is sealed within a hollow sleeve of substantially the same diameter as the oil well tubing in which it is located so that infiltration of mud, water, oil and other deleterious materials to the interior of the joint is prevented.

Still another purpose of the invention is to provide a safety joint in accordance with the preceding objects in which a tool embodying the safety joint may be readily moved into or out of thewell bore when the joint is in a neutral position, and yet which is capable of automatically functioning as a catcher for the associated portion of the tubing string should the latter drop for any reason, as by parting of the string or the like.

An additional object-of the invention is to provide a device which is applicable as a safety joint in various types of operating strings for oil well use on various types of'oil well equipment, such as with well packers, testers and the like. I

Yet a further object of the present invention is to provide an improved anchor and catcher mechanism for use in oil well tubing strings, which anchor and catcher mechanism may be more economically constructed than previous types of anchor and catcher mechanisms, yet which is characterized by a long and trouble-free operating life.

v In addition to the foregoing object and advantages, other desirable features and advantageous aspects of the present invention will become apparent from a reading of the following detailed disclosure in conjunction with a perusal of the accompanying drawings which illustrate my invention.

In the drawings:

FIGURE 1 is a view in elevation showing a portion of an oil well tubing string made up with the anchor-catcher mechanism of the present invention incorporated therein.

FIGURE 2 is an exploded view showing the parts of the safety joint of the invention which is connected in tandem with the tubing string. In FIG. 2, the cylindrical housing and its associated slip elements, which surround the safety joint and are used conjunctively therewith to form the anchor-catcher mechanism of the invention, are removed. Portions of the safety joint mechanism are shown in sectionfor purposes of clarification.

FIGURE 3 is an elevational view of the anchor-catcher mechanism of the present invention as the same appears when it is in a neutral position ready for lowering of the tubing string into the well bore. A portion of the outer cylindrical housing of the mechanism has been broken away and the internal elements of the mechanism are illustrated in section.

FIGURE 4 is an elevational view similar to, FIG. 3, but illustrating the appearance of the mechanism after the tubing string has been rotated by one-third turn to set the anchor mechanism after the string has been placed in position in the well bore.

FIGURE 5 illustrates the position of the elements of the anchor-catcher mechanism after the slips of the mechanism have been retracted radially inwardly to release the anchor and the tubing string in the casing of the well.

FIGURE 6 is a view in elevation of the anchor-catcher device of the present invention with portions of the assembly shown in section to illustrate the position assumed by the elements of the mechanism when the device functions as a catcher to prevent a portion of the tubing string from falling downwardly in the well.

Referring now the drawings in detail, and particularly FIGS. 1 and 2, reference character 10 designates a section of oil well tubing which-is connected at its upper end to a string of tubing extending from the surface of a well bore downwardly therein. The lower end of the section of tubing 10 is threaded with a tapered righthand thread 12. The lower end of the tubing section 10 is threaded into the upper end 14 of an upper sleeve 16. Itwill be noted in referring to FIG. 2 that the upper sleeve 16 is provided with a relatively small threaded bore at its upper end 14 into which the lower end 12 of the tubing section It) is threaded, and is provided at its lower end with a counterbore 18 which is of larger diameter than the bore at the upper end thereof, and which is provided over a portion of its length with righthand threads 20. The threads 20 originate at the lower end 22 of the upper sleeve 16 at the origin of the counterbore 18 and extend upwardly into the counterbore for about half its length.

Threaded into the counterbore 18 byengagement of an externally threaded endportion 24 with the threads 20 of the counterbore is a lower sleeve 26. A seal is established between the lower sleeve 26 and the upper sleeve 16 by the provision of an O-ring 27 which is positioned in a groove provided at the bottom of the external threads of the upper portion 24 of the lower sleeve. Opposite the external threads and inside the upper portion 24 of the lower sleeve 26 are a series of internal threads which are left-hand threads, thus beingopposite in pitch to the external threads on the upper portion 24 of sleeve 26.

Belowthe lower sleeve 26 is an elongated mandrel designated generally by reference character 28. At the upper, end of the mandrel 28, an end portion 343 of reduced diameter is provided and is characterized in being peripherally threaded with a right-hand thread. Adjacent the reduced diameter, externally threaded portion 30 is a portion of larger diameter 32 which is provided with left-hand threads which threads are dimensioned to engage the internal thread of the upper portion 24 of sleeve 26 when the upper end of the mandrel 28 is screwed thereinto. When the mandrel 28 is thus screwed into the lower sleeve 26, the lower portion of the lower sleeve 26 sealingly engages the shank 34 of the mandrel 28 through the instrumentality of an O-ring 36 which is provided adjacent the lower end of the lower sleeve 26.

The shank 34 of the mandrel carries two vertically spaced cam rings, 38 and 40, each of which has two reversely inclined carnming surfaces which meet in a circumferential line. lying radially outwardly from the peripheral plane of the shank 3 At its lower end 42, the mandrel 23 is externally threaded with a right-hand thread for connection to a section of oil well tubing so that the tubing string may be made up below the anchorcatcher mechanism ofthe present invention to any depth which may be desired. Spaced vertically upward from the threaded end portion 42 of the mandrel 28 is a circumferential flange 44 which extends radially outwardly from the mandrel 28. portion 46 of enlarged diameter which carries a radially projecting lug 48.

As afinal element of the internal mechanism constituting the safety joint of the present invention, an internally threaded lock nut49 is provided for securement to the externally threaded upper end 30 of the mandrel 28. The lock nut 49 is of sufficiently small outside diameter to permit it to pass into the counterbore 18 of the upper sleeve 16, but is sufiiciently large in outside diameter to prevent it from passing into the bore through the upper end 24 of the lower sleeve 26. V

In assembling the elements of the safety joint which are illustrated in FIG. 2, the section of tubing ltl may be first .threadedly connected to the upper sleeve 16 by screwing the tubing section It) into the internally threaded upper end 14- of the upper sleeve 16 until it is fully seated. Next, the externally threaded portion 32 of the mandrel 28 is threaded into the lower sleeve 26 to a fully seated status. The lock nut 49 is then screwed onto the externally threaded end portion 30 of the mandrel 28. The lower sleeve 26 is then threaded into the upper sleeve 16 so that the upper sleeve, lower sleeve, lock nut and mandrel occupy the positions shown in FIG. 3 of the drawings. Finally, the lower end portion 42 of the mandrel 28 is threaded into a section of the tubing string and the makeup of the tubing string below the anchorcatcher device of the present inventionis continued in the normal manner.

When the safety joint elements of FIG. 2 have been assembledin the manner described; a cylindrical housing designated generally by reference character 50 is slipped over the FIG. 2 assembly and occupies the position shown in FIGS. 1 and 3. .The cylindrical housing Stl has a diameter such that its downward movement relative to the mandrel 28 will be arrested by the circumferential flange 44. At its upper end, the cylindrical housing 50 is necked down to a smaller diameter so that the downward movement of the housing 50 is also arrested by the abutment of the necked-down upper end portion 52 against the. upper sleeve 16. Adjacent its lower end 54, the housing 50 is provided with a generally T-shaped slot designated generally by reference character 56. The T- shaped slot 56 has a'vertically extending branch 58 and a horizontal branch 64) which intersects the vertically extendingbranch at approximately its midpoint. The horizontal branch 60 is provided at its closed end with a pair of protuberances fill a. The intersection between the branches 58 and 60 of the T-shaped slot 56 provides a pair of tapered portions 6%. The T-shaped slot 56 is engaged by the radially projecting lug 43 in the manner illustrated in FIGS. 3 through 6.

Although the cylindrical housing Ell may be made as a single integrally. formed component of the system, I prefer to utilize a separate upper tubular portion Stla and lower tubular portion Sllb which may be threadedly engaged as illustrated at 61 in FIGS. 3 and 4. The lower tubular portion Stlb of the cylindrical housing 5b is provided with circumferentiallyspaced slots as which accom- Above the flange 4.4 is a cylindrical modate slip elements 64-. The slip elements 64 areprovided with teeth or wickers as at the outer surface thereof and are further provided with four reversely inclined surfaces 68 at the inner side thereof, which surfaces cooperate with the cam rings 38 and 4t) to permit the slips to be moved radially outwardly with respect to the cylindrical housing 59 as the mandrel 28 is moved upwardly and downwardly inside the cylindrical housing. The slips 64- are retained against loss through the slots 62 by toes 7t) formed at the opposite ends thereof and engagingthe interior walls of the cylindrical housing 50 when the slips are moved radially outward by the cam rings 38 and 40 on the mandrel 28.

A plurality of drag springs 72 are spaced circumferentially around the cylindrical housing 51) and are positioned between the slips 64 on the lower tubular portion 5% of the cylindrical housing St). The drag springs '72 are arcuate metal strips which are secured at their upper ends 74 to the cylindrical housing St) by rivets, screws or other suitable means. The lower ends 76 of the drag springs are free and unattached.

Operation The several elements of the present invention having been identified and their relation in the assembled tool established, the operation and functioning of the tool will now be described. The various operative aspects of the anchor-catcher device incorporating the novel safety joint of the present invention may best be understood and followed by referring to FIGS. 3 through 6 of the drawings;

Referring first to FIG. 3, this figure of the drawings shows the anchor-catcher device of the present invention as it is initially made up in a neutral position preparatory to running a string of oil well tubing into the Well. In this position, it will be noted that the lock nut 49 is outtcd against the internal shoulder which is formed by the reduction in diameter from the counterbore 18 to the small bore at the upper end 14 of the upper sleeve 16. The cylindrical housing 50 has been rotated relative to the mandrel 28 so that the radially extending lug 48 is p0sitioned at one end of the horizontal slot 6% of the T-shaped slot 56 and is prevented from slipping out of the horizontal slot 69 by the protuberances 60a. In this position, the cam rings 38 and 40 formed on the shank 34 of the mandrel 28 are out of engagement with the reversely inclined carn surfaces 68 of the slips 64 so that the slips are retracted within their slots 62in the cylindrical housing 50. In other words, the radially projecting lug 48 and the T- shaped slot 56 act as an indexing mechanism for indexing the relative position of the cam rings 33 and dd and theslips 64 during operation of the anchor-catcher device of the invention. With the slips retracted into the cylindrical housing 5%, the tubing string may be lowered in the well borewith only the yielding frictional resistance offered by the drag springs 72 opposing the downward movement of the string in the casing. Any tendency of the cylindrical housing 50 to rotate relative to the mandrel 28 is prevented by the engagement of the radially extend ing lug 48 with the protuberances 60a of slot 60.

' .After the tubing string, including the anchor-catching device, has reached the position in the well bore at which it is desired to operate, the tubing string is anchored in the casing by moving the slips 64 radially outward from the cylindrical housing 59 intoengagement with the in-- ternal walls of the casing. Outward movement of the slips 6% is accomplished by rotating the tubing string onethird of a revolution to the right, or in a clockwise direction, with such rotation being accomplished at the surface.

Since the length of thehorizontal slot 60 corresponds to about one-third the circumference of the cylindrical hous,

ing 5th, rotation of the mandrel 28 one-third of a turn to the right will result in the radially projecting lug 48 being moved from the position showninFIG. 3 to the dashed line position shown in FIG. 4. This movement is effected when the tubing string is rotated one-third of aturn to the right by virtue of the transmission of such rotary move-f ment through the threaded connection between the tubing section lit and the upper sleeve 16, the threaded connection between the upper sleeve 16 and the lower sleeve 26 and the threaded connection between the lower sleeve 26 and theexternally threaded portion 32 of the mandrel 28.

The cylindrical housing 54 is maintained against rotational movement by the yielding frictional engagement of the drag springs 72 with the internal walls of the casing. Thus, as the mandrel'ZS is rotated, the radially projecting lug 48 moves laterally in the slot 66 until it assumes the position shown in dashed lines in FIG. 4. When L16 radially projecting lug 48 has moved to the dashed line position of FIG. 4, an upward pull on the tubing string will cause the lug 48 to move vertically upward in the vertical slot 58 until it has assumed a position at the top of the vertical slot 58 as shown in solid lines in FIG. 4. This position of the radially projecting lug 48 corresponds to the position of the cam rings 38 and 40 and the slips @2- illustrated in FIG. 4. It will be noted that in this relative position of the cam rings 38 and 49 and the slips 6d, the cam rings bias the slips outwardly with respect to the cylindricalhousing t) and cause the wickers 66 of the slips 64 to bite into the surrounding walls of the casing of the oil well. The tubing string is thus firmly anchored against vertical or lateral movement in the well bore and is retained in such anchored status during the production of fluid through the tubing string.

It may be noted that further upward movement of the tubing string relative to the cylindrical casing 56 so as to move the high points of the cam rings 38 and do out of engagement with the high points of the slips 64 is prevented by the positive engagement of the lower end 54 of the cylindrical housing 5t? with the circumferential flange 44 formed near the bottom of the mandrel 28. Further upward movement of the tubing string relative to the cylindrical housing 50 is also prevented by the engagement of the necked down portion 52 of the housing with the upper. end of the upper sleeve 16. It will also be noted that the tapered portions 65!) of the T-shaped slot 56 assure that if an operator has not turned the tubing As the externally threaded portion 32 of the mandrel 28 is unscrewed from the internally threaded upper portion 24- of the lower sleeve 26, the mandrel moves axially downward with respect to the upper sleeve 16 so that the lock nut 49* carried at the upper end of the mandrel moves downwardly in the counterbore 13. This downward movement of the mandrel 28 and the associated lock nut 49 continue until the lock nut butts against the upper end of string for precisely the one-third rotation required. to set causes the cam rings 38--and 40 to move relative to the slips 64 and thus radially project the slips into engagement with the casing of the well or permit them to be radially retracted into the cylindrical housing. With the slips 64 in their radially projecting positions as shown in FIG. 4, the tubing string will be anchored in the well casing until such time as it is desired to remove the string therefrom, At this time, the tubing string is again rotated in a clockwise or right-hand direction so that the rotary movement of the string is transferred to the upper sleeve 16. The lower sleeve 26 is threaded into the threaded portion of the counterbore 18 of the upper sleeve 16 with right-hand threads and thus must rotate with the upper sleeve.

The mandrel 28, by virtue of the engagement of the lug 43 with the vertical slot 58 in the cylindrical housing 50, and also by virtue of the =locking of the cylindrical housing against rotation by reason of the anchoring contact of the slips 64 with the well casing, is retained against rotative movement. Thus, as the upper sleeve 16 and the lower sleeve 26 are rotated to the right or in a clockwise direction, the mandrel 28 must be backed out of or partially unscrewed from thelower sleeve 26 due to the opposite pitch of the external threads on the portion 32 of the mandrel from the threads on the lower end 12 of the tubing section 10 and the threads which join the upper andlower sleeves, 16 and 26, respectively.

the lower sleeve 26. At this time, no further downward movement of the mandrel 28 relative to the upper and lower sleeves 16 and 26, respectively, is possible as a result of further right-hand rotation of the string. The size of the external threads on the upper portion 32 of the mandrel 28 is such that 3 /2 t-u'rns of the tubing string in the right-hand or clockwise direction brings the lock nut 49 into abutting contact with the upper end of the lower sleeve 26. V

When the mandrel 28 has been moved downwardly relative to the upper and lower sleeves, 16 and 26, respectively, to this extent, the cam rings 33 and 40 around the shank 34 of the mandrel are moved out of engagement with the cam surfaces 68 of the slips 64 and the slips are permitted to retract into the cylindrical housing 50. With the disengagement of theslips 64 from the internal walls of the well casing, the tubing string may be easily removed from the well. The position assumed by the radially projecting lug 48 and the safety joint assembly including the lock nut 49- after the tubing string has beenrotated 3 /2 turns in the prescribed manner is illustrated in FIG. 5.

From the foregoing description of'the present invention, it will be perceived that the slips 64 are set to their anchoring position and are retracted to release the tool {from an anchored status by rotation of the tubing string in the same direction. In other words, to set the slips to an anchoring status, the tubing string is first rotated about one-third turn to the right or in a clockwise direction. To release the slips from their anchoring position, the tubing string is further rotated to the right for 3 /2 turns. Further rotation of the tubing string to the right will not affect the released status of the slips 64 since the radially projecting lug 48 assures that the cylindrical housing 50 will be rotated with the tubing string, and no change in the relative position of the mandrel 28 with respectto the cylindrical housing Sit is possible due to the abutting contact of the lock nut49 with the shoulder formed by the upper end of the lower sleeve 26. It is therefore impossible to inadvertently disconnect or part the tubing string by reverse rotation of the string to release the anchor mechanism of the invention. The danger of losing the 'lower portion of the tubing string into the well bore is thus obviated.

A further feature of the present invention is the ability of the described mechanism to automatically function as a catching device for catching the lower portion of the tubing string should the tubing part above the mechanism of the invention. Such parting of the tubing string may occur as the result of excessive metal fatigue in the tubing string after extended pumping, or may be caused by excessive wear of the string against the walls of the casing. The manner in which the anchor-catcher mechanism of the invention functions to catch the lower portion of the tubing string in theevent that the string is in some manner parted or severed at or above the tubing section 10 may best be understood by reference to FIG. 6 of the drawings.

Most often, the tubing string will part after the slips 64 have been released and as an upward pull is exerted on the tubing string to remove the apparatus from the well. Corrosion and the presence of foreign materials may cause the anchor-catcher to be stuck, particularly if it has been in the well for an extended period of time, and an excessive force may have to be exerted to free the mechanism. As the tubing string is parted, the weight of the string below the location of the break in the string 9 is suflicient to cause the tubing string, including the safety joint assembly shown in FIG. 2, to move downward relatively to the cylindrical housing 50 since the cylindrical housing is retarded or restrained against downward movement by virtue of the engagement of the drag springs 72 with the internal walls of the .well casing. Stated differently, when the tubing string is severed at or about the tubingsection 10, the weight of the string below the cylindrical casing 54] causes the safety joint assembly including the mandrel 28 to move downwardly relative to the cylindrical housing 56.

As the mandrel 28 moves downwardly, the radially projecting lug 48 moves downwardly in the T-shaped slot 56 to the position shown in FIG. 6. It will be apparent, of course, that conjunctively with such movement of the radially projecting lug 48, the cam rings 38 and 40 also move downwardly relative to the slips 64. The cam rings 38 and 40 therefore again contact the protuberant portions of the cam surfaces 68 of the slips 64 to force the slips out of the cylindrical housing 50 and into gripping engagement with the internal walls of the casing. As the .Wickers of the slips 64 bite into the walls of the casing,

the downward fall of the lower portion of the tubing strings is arrested, thus avoiding corkscrewing of the tubing resulting from the continued fall of the string, and permitting the parted lower portion of the tubing to be more easily fished from the well bore. It will be noted that the catching function of the mechanism is performed entirely independently of the operation of the safety joint, depending only on the occurrence of downward movement of the mandrel 28 relative to the cylindrical housing 50. x

It will further be noted that, in fishing the lower portion of the parted tubing string out of the well bore, the slips 64 will be retracted into the cylindrical housing 50 at such time as an upward axial force is applied to the tubing section 10. Such force causes the tubing section 10 and the safety joint assembly connected thereto, including the mandrel 28, to move upwardly relative to the cylindrical housing 50. This movement in turn disengages the cam rings 38 and 40 from the cam surfaces 68 of the slips, 64

, to permit the slips to again be retracted into the cylindrical housing. The tool is thus released from its catching status and the lower section of tubing may be easily removed from the well bore. The slips cannot be reset by theupward force because the mandrel 34 and cam rings 38 and 40 have been moved to their lowermost position by the threads 32 during the right-hand rotation of the tubing 10 to release the slips 64. Thus, the maximum relative movement that can occur between the hous ing 50 and the cam rings 38 and 40 is just sufiicient to move the cam rings 38 and 40 into the enlarged portion of the inclined surface 68 on the slips 64 in which position the slips 64 are released.

If the tubing string should part during the lowering of the apparatus into the well, the slips 64 cannot be set because the lug 48 is in thehorizontal branch 60 of the T-shaped slot 56, thereby locking the housing t relative to the mandrel 28. There must be relative movement thercbetween to set the slips 64. Should the tubing string part during the lowering thereof into the well, the lower part of the tubing string can be removed with conventional fishing equipment by simply latching onto the lower part of the tubing string and pulling up.

If the tubing string should part while the slips 64 are in engagement with the well casing or bore, the safety joint assembly cannot fall. To remove the assembly from the well, it is necessary. to latch onto that part of the tubing string remaining in the well and rotate the mandrel to the right, as previously described, to release the slips 64. After releasing the slips 64 by rotation, the assembly can be pulled from the well. Also, as previously described, the slips 64 cannot become set during the upward movement in the well.

From the foregoing description of the invention, it will have become apparent that a novel and highly useful safetyjoint has been proposed which may be utilized in a number of applications, only one of whichis represented by the improved anchor-catcher assembly herein described by way of example. Thus, although the novel safety joint forming the basic feature of this invention has been that the safety joint may be embodied in other oil well tools, such as packers, testers, and the like.

Also, the improved anchor-catcher assembly shown and described herein may be utilized with other types of connected sections of tubing other than oil well tubing,

strings, and may be used equally well in the case of strings of rod or other solid cylindrical sections. The safety joint assures that all operations involving the rotation of a string of rod or tubing sections may be carried out with a maximum of safety so that inadvertent disconnection or parting of the string by operator error in rotating the tubing is avoided. The manner in which the safety joint is constructed, including the strategic positioning of the O-ring seals aroundthe threaded connections formed during assembly of the safety joint assure that the joint will be protected from the infiltration and ingress thereto of deleterious material, such as mud, oil, water, dust and the like. Therefore, the joint while, being relatively simple in construction and inexpensively manufactured, is also characterized by a long and trouble-free operating life.

Although a preferred embodiment of the safety joint constituting thebasic feature of the invention has been hereinbefore described, and an especially useful adaptation of the safety joint for use in combination with an oil well tubing anchor-catcher device has been illustrated and discussed in detail by way of example, the details of these illustrative embodiments hereinbefore described are not intended to limit the scope of the invention, Thus, certain modifications and innovations will readily occur to those skilled in the art which may alter the appearance of the device and some of its modes of operation without departure from the basic principles underlying the invention. Insofar as such innovations and modifications con tinue to rely upon the basic inventive principles herein disclosed, these changes are deemed to fall within the spirit and scope of the invention except as the same may be necessarily limited by the language of the appended claims.

I claim:

1. An oil well tubing anchor-catcher comprising:

(a) tubular sleeve means connected at its upper end to a first section of said oil well tubing for rotation therewith in one direction of rotation, said sleeve means having an internally threaded bore at its lower end and a circumferential, inwardly extending shoulder at the upper end of the threads of said bore and spaced from said tubing section;

(Z2) elongated mandrel means having a portion adjacent one of its ends threaded into said threaded bore for unscrewing therefrom when said mandrel is held stationary and said upper section of tubing is rotated in said one direction, said mandrel means having its other end connected to a second section of said oil well tubing;

(c) shoulder means on said one end of said mandrel means inside said tubular sleeve means between said first tubing section and said circumferential, inwardly extending shoulder and axially movable in said sleeve means upon movement of said mandrel means relative to said sleeve means, saidshoulder means cooperating with said first-mentioned shoulder to arrest the downward movement of said mandrel means relative to said sleeve means when said tubing is rotated in said one direction and said mandrel is held stationary; and (d) radially movable slip means positioned slidably i. 1 around said mandrel means and responsive to axial movement of the mandrel means relative to said slip means to lrnoveradially into and out of engagement with the well bore surrounding said tubing to anchor said tubing in said well bore, said slip means including means engaging the well here surrounding the tubing to prevent rotation of said slip means relative V to the well bore.

2. An oil well tubing anchor-catcher as claimed in claim 1 wherein said one end of said mandrel means projects above said threaded bore and said circumferential, inwardly extending shoulder into said sleeve means;

' and wherein said shoulder means comprises a lock nut threaded on said one end of said mandrel means and vertically spaced above said circumferential, inwardly extending shoulder when said mandrel means is threaded 7 into said internally threaded bore as far as possible.

3. An oil well tubing anchor-catcher as claimed in claim 1 wherein said tubular sleeve means comprises:

(a) an upper sleeve threadedly connected at its upper end to said first section of oil well tubing and having an enlarged counterbore at its lower end, which counterbore is internally threaded over a portion of its length;

(b) a lower sleeve threaded into the counterbore of said upper sleeve by threads corresponding in pitch to the threads connecting said upper sleeve to said first tubing section and forming with its upper end said inwardly extending circumferential shoulder, said lower sleeve being internally threaded with threads of opposite pitch from said other threads and engaging thereby the threaded portion of said mandrel means adjacent said one end thereof whereby said mandrel means is threaded into said lower sleeve by rotation in the opposite direction from the direction of rotation required to threadedly engage said upper sleeve with said first section of oil well tubing and said lower sleeve. 4. An oil well tubing anchor-catcher as claimed in claim 1 wherein said slip means comprises:

(a) a housing around said mandrel means and axially slidable relative'the'reto;

(b) at least one slip mounted in said housing and movable radially therefrom for engagement with the well bore in which said tubing is located;

and further characterizedto include actuating means on'said mandrel means operable in response to axial movement of said mandrel means relative to said housing for radially extending said slip from said housing. I

5. An oil well tubing anchor-catcher as claimed in claim 4 wherein the means engaging the well bore surrounding said tubing for retaining said slip means against rotative movement when said slips are retracted and said tubing, sleeve means and mandrel means are rotated is located on said housing.

6. An oil well tubing anchor-catcher as claimed in claim 4- and further characterized to include means for indexing the relative axial positions of said housing and said mandrel means by rotative movement of the oil well tubing string.

7. An oil well anchor-catcher as claimed in claim 6 wherein said indexing means comprises:

'(a) a generally T-shaped slot in said housing having a vertical slot and a horizontal slot intersecting said vertical slot at the center thereof; and

(Z1) a lug on said mandrel means engaging said T- shaped slot for retaining said mandrel means against axial movement relative to said housing when said lug moves in said horizontal slot during rotation of said mandrel means, and for permitting relative axial movement between said mandrel means and said housing when said lug moves in said vertical slot.

8. An oil well tubing anchor-catcher as claimed in claim 4 wherein said actuating means comprises circumferential cam 'rings on said mandrel means operative to radially extend said slip when said mandrel means is moved upwardly and downwardly relative to said housing.

9. An oil well tubing anchor-catcher as claimed in claim 8 wherein said slip has a radially inwardly projecting cam surface thereon and said cam rings include reversely inclined surfaces engaging the cam surface of said slip during axial movement of said mandrel means relative to said housing whereby said slips may be moved radially outwardly from said housing responsive to upward and downwardmovement of said mandrel means relative to said housing.

10. An anchor for a tubing string comprising:

(a) a vertically elongated housing adapted to be slidable in a well bore; (12) slips mounted in said housing and movable radially therefrom into anchoring engagement with the well bore;

(c) a mandrel rotatably and slidably mounted in said housing;

(at) actuating means on said mandrel operable in response to vertical movement of said mandrel in said housing for moving said slips radially outwardly of the housing for anchoring engagement with a well bore;

(e) means for fixedly securing said mandrel to a tubing stringformovement with said tubing string; (1) means on said mandrel responsive to predetermined rotation of said tubing string and mandrel in one direction relative to said housing to permit vertical movement of said actuating means to selectively urge said slips outwardly of said housing, said means also being responsiveto additional rotation insaid one direction to release said slips for retraction into.

said housing; and,

(g) means on said housing engageable with the well bore for yielding by resisting movement of said housing in said well bore and to move said actuating means.

to a position wherein said actuating means cannot be engaged by said slips.

11. The combination claimed in claim 10 wherein said actuating means is operable upon relative 1 downward movement of said mandrel in said housing to radially extend said slips into anchoring engagement with a well bore.

12. The combination claimed in claim 10 wherein said actuating means includes circumferentially extending cooperating cam surfaces on said mandrel and on said slips.

13. The combination claimed in claim 12 wherein at least one of said cammed surfaces is reversely inclined for radially projecting said slips in response to both upward and downward movement of said mandrel in said housing.

References Cited by the Examiner UNITED STATES PATENTS 2,832,419 4/58 Webber 166-2l6 X 2,832,422 4/58 Cross et al. 166216 3,658,526 10/62 Douglass et al. l66-2l6 3,077,933 2/63 Bigelow l662l7 BENJAMIN HERSH, Primary Examiner.

CHARLES E. OCONNELL, Examiner. 

1. AN OIL WELL TUBING ANCHOR-CATCHER COMPRISING: (A) TUBULAR SLEEVE MEANS CONNECTED AT ITS UPPER END TO A FIRST SECTION OF SAID OIL WELL TUBING FOR ROTATION THEREWITH IN ONE DIRECTION OF ROTATION, SAID SLEEVE MEANS HAVING AN INTERNALLY THREADED BORE AT ITS LOWER END AND A CIRCUMFERENTIAL, INWARDLY EXTENDING SHOULDER AT THE UPPER END OF THE THREADS OF SAID BORE AND SPACED FROM SAID TUBING SECTION; (B) ELONGATED MANDREL MEANS HAVING A PORTION ADJACENT ONE OF ITS ENDS THREADED INTO SAID THREADED BORE FOR UNSCREWING THEREFROM WHEN SAID MANDREL IS HELD STATIONARY AND SAID UPPER SECTION OF TUBING IS ROTATED IN SAID ONE DIRECTION, SAID MANDREL MEANS HAVING ITS OTHER END CONNECTED TO A SECOND SECTION OF SAID OIL WELL TUBING; (C) SHOULDER MEANS ON SAID ONE END OF SAID MANDREL MEANS INSIDE SAID TUBULAR SLEEVE MEANS BETWEEN SAID FIRST TUBING SECTION AND SAID CIRCUMFERENTIALLY, INWARDLY EXTENDING SHOULDER AND AXIALLY MOVABLE IN SAID SLEEVE MEANS UPON MOVEMENT OF SAID MANDREL MEANS RELATIVE TO SAID SLEEVE MEANS, SAID SHOULDER MEANS COOPERATING WITH SAID FIRST-MENTIONED SHOULDER TO ARREST THE DOWNWARD MOVEMENT OF SAID MANDREL MEANS RELATIVE TO SAID SLEEVE MEANS WHEN SAID TUBING IS ROTATED IN SAID ONE DIRECTION AND SAID MANDREL IS HELD STATIONARY; AND (D) RADIALLY MOVABLE SLIP MEANS POSITIONED SLIDABLY AROUND SAID MANDREL MEANS AND RESPONSIVE TO AXIAL MOVEMENT OF THE MANDREL MEANS RELATIVE TO AXIAL MEANS TO MOVE RADIALLY INTO AND OUT OF ENGAGEMENT WITH THE WELL BORE SURROUNDING SAID TUBING TO ANCHOR SAID TUBING IN SAID WELL BORE, SAID SLIP MEANS INCLUDING MEANS ENGAGING THE WELL BORE SURROUNDING THE TUBING TO PREVENT ROTATION OF SAID SLIP MEANS RELATIVE TO THE WELL BORE. 